I have APD, along with that I am Bi-Polar. These traits, moods, habits, thought processes spill into my personal life and can be a detriment to all relationships I have.
When I was younger ( basic school to 3rd grade) I was a terror, destructive, had an aptitude for musical instruments, but all round a little shit, and it was while answering my psychiatrist's question about my childhood with her looking at me confused I realized something was wrong with me as a child but it was dismissed as bad behaviour. She had also asked, Why wasn't I tested while showing such behaviour? I had joked about insanity being the norm in my home, but the truth is I learnt how to pretend that everything is okay, to match my behaviour with those around me. Maybe this is why most of us have different personalities for different group of people.
My point is every child should see a child psychologist for a couple years and every parent should learn child psychology as to be better parents. Chances are your kid is just shy, chances are they don't understand how they feel, chances are they can't emote well and so they misbehave.
My point is my kids gonna spend time in therapy to ensure they are mentally healthy so in the long run they are functional adults ( read: not like me) .